1. Technical Field
The present invention relates in general to structural anchors and, in particular, to an improved system, method, and apparatus for a structural lug formed from multiple dissimilar materials such as metals and composite laminates.
2. Description of the Related Art
In the prior art, structural anchoring connectors known as “lugs” are very common and important structures in the aerospace and other industries. Lugs are used as a means of connecting two or more structures and act as primary load paths for the underlying structures. Lugs formed from metallic materials such as alloys are the most common and are widely used for many types of applications. Lugs formed from entirely from non-metallic materials (e.g., composite materials) have become increasingly common as well for other types of applications.
Unfortunately, lugs formed from both types of materials have some disadvantages. Metallic lugs are heavy and are subject to fatigue cracking. Typically, variables such as damage tolerance are used to determine the size of a lug for a given application. In addition, metallic components must be large enough to sustain cyclical loading over their lifetime.
The newer, all-composite lugs usually do not have the same issues with fatigue and fatigue cracks as metallic lugs. However, the primary concern with non-metallic lugs is with the ultimate failure mode of a composite structure. For example, composites typically have a brittle failure mode. This means that if a composite lug suffers a large enough crack it will fail catastrophically very quickly. In contrast, a metallic lug has a more ductile failure that may be prolonged before complete failure. Thus, an improved lug solution that combines the best features of both metallic and composite materials into a single structure would be desirable.